Integration and optimization of a waste incineration power plant-power to gas hybrid system for SNG production

Production of SNG from a waste incineration power plant-power to gas hybrid system can reduce greenhouse gas emissions and storage renewable energy on a massive scale. However, an optimization of this process is still needed due to the low efficiencies of waste incineration power plants and poor waste heat utilization. In this paper, an integrated process was modeled by using Aspen Plus software. Based on energy balance analysis, an innovative way was proposed to improve the efficiency of a waste incineration power plant by recovering the methanation reaction heat. A two-stage methanation process was designed where an adiabatic fixed bed reactor and a low-temperature fluidized bed reactor connected in series. Energy recovered from the hot gas flow at the outlet of the fixed bed reactor was used to improve steam parameters and optimize the steam cycle, and the power generation efficiency was increased from 22.05% to 31.72%. The low-temperature fluidized bed reactor ensured the quality of synthetic natural gas. Moreover, the type of flue gas recirculation in the waste oxy-combustion process had an impact on the overall process efficiency. And the energy conversion efficiency was higher with dry flue gas recirculation. The above results have some guidance for improving process economy and competitiveness. © 2022, Chemical Industry Press Co., Ltd. All right reserved.